Developer for diazo-type printing plates and the use thereof



United States Patent 3,201,241 DEVELQIER FOR DlAZtl-TYPE PRINTING PLATES AND THE USE THEREQF Johannes Munder and Hans Heiss, Wieshaden-liiehrich, Gerhard Fritz, Wieshaden, and Dieter flsswald and Hans Egon Heels, Wieshaden-Biehrich, Germany, assignors, by rnesne assignments, to Azoplate (Jorporation, Murray Hill, Ndh, a corporation of New Jersey No Drawing. Filed .luly 11, 1961, Ser. No. 123,114 Claims priority, application Germany, July 29, 1960, K 41,325 26 Claims. (fit. 96-49) The present invention relates to a developer for photomechanical printing plates.

It is known to prepare planographic printing plates photomechanically by a process in which plates or foils .made of metal or paper, e.g. aluminum, which have been provided with coatings of water-insoluble, lightsensitive substances, preferably consisting of diazo compounds, i.e. presensitized sheets, are illuminated on the light-sensitive side through a master and then the exposed coating is developed to an image by means of dilute aqueous alkaline solutions. Known developers for these coatings are, for example, aqueous solutions of dior trisodium phosphate or of watersoluble organic bases of low concentrations. According to the type of the light-sensitive substance used, positive or negative printing images are obtained from the originals by the use of the alkaline developers, this being dependent upon whether it is the portions affected by the light or the portions not affected by the light that are removed by the developer.

As light-sensitive substances, quinone diazides have also been used, o-quinone diazides having found practical application for positive-working offset printing plates and p-quinone diazides for negativewvorking printing plates.

If coatings consisting of such compounds, or mixtures of such compounds, or mixtures of such compounds with resins are applied to a suitable support, e.g., an aluminum plate or paper foil, and are illuminated through a master, the coating is chemically changed in such a way that the portions affected by the light are less soluble in alkaline media of suitable concentration than are the portions unaifectcd by the light. Alkaline developer solutions of this kind, with which the portions unaffected by the light can be dissolved away, have consisted of aqueous solutions of alkali phosphates or silicates or of organic bases, such as ethanolamine. However, with these developer solutions the portion of the coating that have been illuminated are also partially dissolved away. For this reason, the length of the runs obtained with the printing plates produced is subject to variation according to the duration of the developer action.

A developer for photomechanical printing plates has now been found which consists of an aqueous solution which, in addition to an alkaline-acting substance, contains salts or oxides or hydroxides of the metals beryllium, mercury, calcium, strontium, barium, bismuth or lanthanum that are soluble in aqueous alkaline media and possibly also complex formers and/or water-soluble substances of higher molecular weight.

The alkaline-acting substances may be the basic substances used in the developer fluids for printing foils having diazo coatings, namely both organic and inorganic, weak and strong alkalis, the latter preferably in dilute form; examples are: water-glass, sodium metasilicate, potassium hydroxide, sodium hydroxide, diethylamine, triethylamine, ethanolarnine, diethanolamine and triethanolamine. Mixtures of these alkalis may also be used.

Of the inorganic alkaline-acting substances, the silicates have proved particularly advantageous, particularly the 3,201,241 Patented Aug. 17, 1965 lanthanum that are to be used in accordance with the invention are added in small quantities, namely about 0.001 percent to about 0.05 percent, preferably about 0.02

to 0.04 percent by weight. The effect depends chiefly on one or more of the cations of the metals mentioned above being present in the solution and the preference is for metals of the second group, particularly the alkaline earth metals. The cations are used, in addition to the oxides and hydroxides, in the form of their salts with inorganic and organic acids, provided they are readily, or at least moderately, soluble in alkaline aqueous solutions.

As the inorganic acids with which the salts are formed, the hydrohalides and nitric acid are preferred. As the organic acids, aliphatic mono and polycarboxylic acids such as formic acid, acetic acid, propionic acid, maleic acid, malonic acid, adipic acid and fumaric acid are primarily used.

To increase the solubility of the salts, oxides or hydroxides in alkaline media, complex formers may be added to the developer solution. In particular, complex formers which form 5 or 6-membered ring chelates such as hydroxyl compounds, hydroxy carboxylic acids, amino carboxylic acids, enolizable polycarbonyl compounds, nitrogen compounds containing hydroxyl and carboxyl groups, phenols, e.g., diethyl barbituric acid, citric acid, tartaric acid, saccharic acid, glycolic acid, adipic acid, ascorbic acid, Eriochrome Black R, Alizarin Yellow GG, salicylaldehyde, 2-hydroxyacetophenone, laevulic acid, salicylic acid, Trilon B, acetylacetone, pyrocatechol, S-benzene azo salicylic acid, Z-acetyl-l, 4-c1esol, 6-acetyl-l, 3-cresol, dibenzoyl methane, and 8-hydroxy quinoline are suitable.

It is frequently advantageous for the complex formers to be added in a quantity in excess of that. stoichiometrically required for the complex formation with the cation, as the coating treated therewith becomes more strongly anchored to the support. This results in an improved resistance of the developed image against the developer,

which, in turn, causes higher runs of the printing plate.

Water-soluble substances of high molecular weight which increase the viscosity can also be added to the developer solutions, e.g., polyglycols, such as polyethylene glycols having a molecular weight of 300 to 10000, carboxymethyl cellulose, cellulose others such as methyl cellulose, ethyl cellulose and polyvinyl alcohols. The developer solution should have a pH value between 10.5 and 12.2, preferably between 10.9 and 11.5.

The developer of the invention is suitable for the development of photomechanical printing plates consisting of a support coated with a light sensitive diazo coating. In particular, it is suitable for the development of printing plates of this type in which the light-sensitive coating, that has been exposed to light in known manner, consists at least in part of one or more p-quinone-diazide compounds of the general formula I so,

I at

group X and in which the residues may be substituted, 5 R is hydrogen; alkyl, alkoxy or halogen, and X stands for S0 or the CO-group.

Formulae of exemplary compounds are as follows:

FORMULA 1 FORMULA 6 OCH FORMULA 2 FORMULA 3 FORMULA 8 s H o l s I N /fi FORMULA 4 OCH3 Such p-quinone diazide compounds may be prepared, for example, in the followingmanner:

(1) 1-chloro-4nitro-benzene-Z-snlfochloride is reacted with an aromatic base to produce the 1-chloro-4-nitrobenzene-sulfarylamides. These intermediate products are condensed in solvents with aryl sulfonamides in the presence of copper powder and alkali carbonate, the chlorine in the 1-position then being replaced by the aryl sulfonamide residue. The nitro compounds thus obtained can be reduced by known processes, e.g. with sodium dithionite, and theamines thus obtained diazotized in Water-miscible solvents, e.g..in a dimethylformamide/glacial acetic acid mixture. The iminoquinone diazides precipitate out for the most part in the form of sparingly soluble compounds or they can be precipitated by the ad dition of water.

(2) 4-nitro-1-amino-benzene-Z-sulfonic acid is reacted with aromatic sulfo-chlorides and the l-arylsulfaminolnitro Z-benZene sultonic acids obtained are converted into the sulfochlorides which, in turn, are reacted with arematic bases. The nitro compounds obtained are further processed as described above under 1.

The development of the exposed reproduction material with the alkaline developer liquid is in known manner, e.g., by immersion or, particularly, by wiping over with a cotton pad or a cloth soaked in the developer liquid. A brush may also be used for the application of the developer solution.

As a result of the addition of the metal cations in complex or non-complex form, the developer liquids described above, which contain about 0.3 to 5 percent by weight, preferably about 0.8 to 1.5 percent, of one or more of the alkaline substances listed, about 0.001 to 0.05 percent by weight, preferably 0. 02 to 0.04. percent, of one or more of the salts, oxides or hydroxides of the metals mentioned, about 0.001 to 0.25 percent by weight, preferably about 0.07 to 0.1 percent, of complex formers and about C to 1.5 percent, by weight, preferably 0.2 to 0.8 percent, of additives such as polyglycols, enable a considerablygreater number of prints to be prepared from printing plates developed with such a developer than from those developed using an otherwise identical developer solution to which the cations of the invention have not con added, because the image portions of the printing plate are to a much lesser extent attacked by the developer of the invention. For example, an exposed aluminum printing plate, the light-sensitive coating of which is applied in the form of a 1.3 percent solution of a compound corresponding to the following formula by cast-coating upon an aluminum plate mounted on a rotating support and then dried, can be immersed in a solution containing 12 g. of sodium metasilicate -5H O per liter for only 5 minutes before the image disappears. If 0.2 g. of barium hydroxide, or an equivalent quantity bf a suitable barium complex salt, is added to the solution, the same plate can be treated for 60 minutes with the developer before the image undergoes an attack of equal intensity.

The invention will be further illustrated by reference to the following specific examples:

Example 1 An aluminum foil mounted on a rotating support was cas -coated with a thin, homogeneous, light-sensitive coating of a 1.3 percent solution in ethylene glycol monomethyl ether of the compound corresponding to Formula 2 above and then dried in a hot air current. The presensitized material thus prepared was illuminated through a transparent master and then rubbed over witha cotton pad soaked in one of the solutions described below and then rinsed with water and dried. In this development process, the non-illuminated portions of the light-sensitive coating are removed.

The foil thus obtained, carrying a reversed image of the master, was inked up in the image portions with greasy ink and then prints were prepared in lrnown manner.

- As developer fluids for the treatment of exposed coatings, the solutions listed by way of example below have proved satisfactory.

(a) A solution of 10.0 parts by weight of sodium metasilicate-9H O, 0.3 part by weight of the calcium complex of Alizarin Yellow GG and 4.0 parts by Weight of polyethylene glycol 6000 in 1000 parts by volume of water. The solution has a pH value of 11.2.

(b) A solution of 10.0 parts by weight of sodium metasilicate, 0.1 part by weight of calcium chloride and 3.0 parts by weight of polyethylene glycol 6000 in 1000 parts by volume of water. The solution has a pH value of 11.2. t

(c) A solution of 20.0 parts by weight of sodium metasilicate-5H 0, 0.3 part by weight of barium acetyl acetonate and 3.0 parts by weight of polyethylene glycol 6000 in 1000 parts by volume of water. The solution has a pH value of 11.3.

Example 2 In the manner described in Example 1, an aluminum foil was coated with the light-sensitive compound corresponding to Formula 3 above and then developed to a printing plate. A printing plate having a reversed image of the master is obtained.

The developer solution used consisted of 10 parts by weight of sodium metasilicate-9H 0, 0.3 part by weight of barium hydroxide and 0.3 part by weight of 2-acety1- 1,4-cresol in 1000 parts by volume of water.

Example 3 In the manner described in Example 1, an aluminum foil was coated with the light-sensitive compound corresponding to Formula 4 above and then developed to a printing plate. A printing plate having a reversed image of the master is obtained.

As a developer solution, either (a) A solution of 10 parts by weight of sodium metasilicate-9H O and 0.3 part by weight of a mercury (11)- complex of 5-benzene-azosalicylic acid in 1000 parts by "volume 'of water or t (b) A solution of 10 parts by weight of sodium metasilicate-9H O and 03 part by weight of calcium nitrate in 1000 parts by volume of Water may be used.

Example 4 weight of sodium metasilicate-9 H O, 0.3 part by weight of diethyl barbituric acid sodium salt and 0.3 part by weight of strontium hydroxide in 1000 parts by volume of water was used.

Example 5 In the manner described in Example 1, an aluminum foil was coated with the light-sensitive compound corre sponding to Formula 6 and then developed to a printing plate. A printing plate having a reversed image of the master is obtained.

As a developer, a solution of (a) 4 parts by weight of sodium metasilicate-9H O and 0.3 part by weight of lanthanum oxide in 1000 parts by volume of water or (b) 4 parts by weight of sodium metasilicate-9H O, and 0.3 part by weight of bismuth hydroxide and 0.3 part by volume of acetylacetone in 1000 parts by volume of water or (c) 50 parts by volume of diethylamine and 300 parts by weight of calcium acetate in 1000 parts by volume of water may be used.

Example 6 In the manner described in Example 1, an aluminum foil is coated with the light-sensitive compound corresponding to Formula 7 and then developed to a printing plate.

A printing plate having a reversed image of the master is obtained.

As a developer, a solution of:

(a) 7 parts by weight of sodium metasilicate-9H O and 0.3 part by weight of beryllium oxide in 1000 parts by volume of water or (b) 50 parts by volume of water glass, 0.3 part by weight of barium chloride and 0.3 part by volume of acetylacetone in 1000 parts by volume of water or (c) 5 parts by weight of potassium hydroxide and 0.3 part by weight of strontium hydroxide in 1000 parts by volume of water may be used.

Example 7 1.3 parts by weight of the diazo compound corresponding to Formula 7 are dissolved in a mixture of 80 parts by weight of ethylene glycol monomethyl ether and 20 parts by weight of butyl acetate. A paper foil, which is provided on one side with a layer consisting of casein and clay hardened with formaldehyde, prepared in accordance with US. Patent 2,534,588, is coated with this solution on a rotating plate. The coating is well dried in a hot air current. The foil thus sensitized is illuminated through a transparent master with an arc lamp, as described in Example 1. The image produced is developed by wiping over with a cotton pad which has been soaked in a solution of the following composition: 7.5 parts by weight of sodium metasilicate 91-1 0, 0.3 part by weight of barium chloride, 0.3 part by volume of acetylacetone, and 1000 parts by volume of water. From a negative original a yellow-green positive image is obtained which is inked up with greasy ink and used a printing master. The resistance of the image to this developer is considerably greater than to a similar developer to which barium chloride and acetylacetone have not been added.

Example 8 In the manner described in Example 1, an aluminum foil was coated with the light sensitive compound corresponding to Formula 8 and then developed to a printing plate. A printing plate having a reversed image of the master is obtained.

The developer used consisted of a solution of 10 parts by weight if sodium metasilicate -9H O and 0.3 part by weight of strontium hydroxide in 1000 parts by volume of water.

8 Example 9 In the-manner described in Example 1, an aluminum foil was coated with the light sensitive compound corresponding to Formula 9 and then developed to a printing plate. A printing plate having a reversed image of the master is obtained.

The developer used consisted of a solution of 10 parts by weight of sodium metasilicate -9H O and 0.3 part by weight of barium chloride in 1000 parts by volume of water.

It will be obvious to those skilled in the art that many modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.

What is claimed is:

1. A developer for planographic printing plates of the type including a light-sensitive diazo compound compris ing an aqueous solution of at least of about 0.3 to 5 percent by weight one alkaline-acting substance selected from the group consisting of alkali metal compounds, alkylamines and hydroxy-alkylamines and about 0.001 to 0.05 percent by weight of at least one compound of an element selected from the group consisting of beryllium, mercury, calcium, strontium, barium, bismuth, and lanthanum, capable of cation formation in an aqueous medium.

2. A developer according to claim 1 including, in addi tion, a complex-forming compound.

3. A developer according to claim 1 including, in addition, a water-soluble compound of high molecular weight.

4. A developer according to claim 1 in which the alkaline-acting substance is a water-soluble alkali metal metasilicate.

5. A developer according the claim 1 in which the alkaline-acting substance is a hydroxy alkylamine.

6. A developer according to claim 1 in which the compound is selected from the group consisting of salts, oxides and hydroxides.

7. A developer according to claim 2 in which the complex-forming compound is one which forms a ring chelate.

8. A developer according to claim 3 in which the watersoluble compound of high molecular weight is a polyethylene glycol.

9. A process for developing a planographic printing plate of the type including a light-sensitive diazo compound which comprises treating the light-exposed coating thereof with a developer comprising an aqueous solution of about 0.3 to 5 percent by weight of at least one alkaline-acting substance selected from the group consisting of alkali metal compounds, alkylamines and hydroxyalkylamines and about 0.001 to 0.05 percent by weight of at least one compound of an element selected from the group consisting of beryllium, mercury, calcium, strontium, barium, bismuth, and lanthanum, capable of cation formation in an aqueous medium.

10. A process according to claim 9 in which the developer includes, in addition, a complex-forming compound.

11. A process according to claim 9 in which the developer includes, in addition, a water-soluble compound of high molecular weight.

12. A process according to claim 9 in which the alkaline acting substance is a water-soluble alkali metal metasilicate.

13. A process according to claim 9 inwhich the alkaline-acting substance is a hydroxy alkylamine.

14. A process according to claim 9 in which the compound is selected from the group consisting of salts, oxides and hydroxides.

15. A process according to claim ;10 in which the complexaforming compound is one which forms a ring chelate.

16. A process according to claim :11 in which the watersoluble compound of high molecular Weight is a polyethylene glycol.

'17. A process according to claim 9 in which those pora 9 tions of the light-exposed coating which were not struck by light comprise a compound having the formula 19. A process according to claim 9 in which those portions of the light-exposed coating which were not struck by light comprise a compound having the formula:

20. A process according to claim 9 in which those portions of the light-exposed coating which were not struck by light comprise a compound having the formula H a a 1 Q1. A process according to claim 9' in which those portions of the light-exposed coating which were not struck by light comprise a compound having the formula .22. A .process according to claim 9 in which those portions of the light-exposed coating which were not struck by light comprise a compound having the formula CHg-(EH-CH:

Q-SOPNH-Q-Ocm '23. A process according to claim 9 in which those portions of the light-exposed coating which were not struck by light comprise a compound having the formula l i N I 2 4. A process according to claim 9 in which those portions of the light-exposed coating which were not 0 struck by light comprise a compound having the formula I t a '25. A process according to claim 9 in which those portions of the light-exposed coating which were not struck by light comprise a compound having the formula:

C53 /CH3 CH 26. Aiprocess according to claim 9 in which those 20 portions of the light-exposed coating which were not struck by light comprise a compound having the formula:

l i N PHILIP E.

2 J, References Cited by the Examiner UNITED STATES PATENTS FOREIGN PATENTS 1/55 Germ-any.

' NORMAIN G. TORCHIN, Primary Examiner.

MANGA'N, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,201,241 August 17, :1965

Johannes Munder et a1.

It is hereby certified that error appears in the aboire numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 7, line 59, after "used" insert as line 73, for "if" read of column 8, line 19, strike out "Of, at least" and insert the same after "weight" in line 20, same column 8.

Signed and sealed this 15th day of February 1966.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. A DEVELOPER FOR PLANOGRAPHIC PRINTING PLATES OF THE TYPE INCLUDING A LIGHT-SENSITIVE DIAZO COMPOUND COMPRISING AN AQUEOUS SOLUTION OF AT LEAST OF ABOUT 0.3 TO 5 PERCENT BY WEIGHT ONE ALKALINE-ACTING SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF ALKALI METAL COMPOUNDS, ALKYLAMINES AND HYDROXYL-ALKYLAMINES AND ABOUT 0.001 TO 0.05 PERCENT BY WEIGHT OF AT LEAST ONE COMPOUND OF AN ELEMENT SELECTED FROM THE GROUP CONSISTING OF BERYLLIUM, MERCURY, CALCIUM, STRONTIUM, BARIUM, BISMUTH, AND LANTHANUM, CAPABLE OF CATION FORMATION IN AN AQUEOUS MEDIUM. 